Department of Biological Sciences - Undergraduate Honors ThesesCopyright (c) 2017 Florida International University All rights reserved.http://digitalcommons.fiu.edu/bio_honors
Recent documents in Department of Biological Sciences - Undergraduate Honors Thesesen-usThu, 07 Dec 2017 08:16:41 PST3600Characterization of DNA methylation in the Flat tree oyster (Isognomon alatus) and its correlation with environmental abiotic factorshttp://digitalcommons.fiu.edu/bio_honors/80
http://digitalcommons.fiu.edu/bio_honors/80Fri, 28 Apr 2017 12:09:58 PDT
Organisms spanning numerous taxa have been shown to mediate stress responses by utilizing epigenetic mechanisms, notably DNA methylation. This study aimed to characterize the seasonal patterns in DNA methylation in the gill tissue of the flat tree oyster (Isognomon alatus) and its response to temperature, pH and salinity variations in Miami’s Northern Biscayne Bay. Flat tree oyster specimens attached to mangrove prop roots by their byssus were sampled from ten distinct sites across the bay that differed by their geographical and physicochemical characteristics. Quantification of DNA methylation from gill tissue show a sinusoidal-like seasonal pattern throughout time. Despite a clear seasonal trend, analyses revealed that there is no significant correlation between abiotic parameters (temperature, pH, salinity) and variations of DNA methylation. On the other hand, this report showed that methylation levels of oysters were highest at sites with the greatest potential sources of pollution. Further studies are required to determine if water pollutants or other chemical factors may be influencing seasonal patterns in DNA methylation and if observed seasonal trends are consistent throughout subsequent years.
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Michelot MichelEFFECT OF SYMBIOTIC STATE ON THE PROTEOME OF EXAIPTASIA PALLIDAhttp://digitalcommons.fiu.edu/bio_honors/79
http://digitalcommons.fiu.edu/bio_honors/79Fri, 28 Apr 2017 08:15:36 PDT
Symbiosis is widespread among shallow-water invertebrates including corals. Most reef corals hold an intracellular mutualistic relationship with photosynthetic dinoflagellates of the genus Symbiodinium. Different species confer different physiological traits on their host, such as thermal tolerance. However, corals are limited in the number of species of Symbiodinium they can host. The mechanisms that define this host specificity as well as those that help maintain symbiosis are not well understood. This study sought to determine how the proteomic profile differs depending on Symbiodinium type and symbiotic state. Exaiptasia pallida, a sea anemone, is used as a model to characterize cnidarian symbiosis. This study determined the proteomic differences between anemones hosting their native Symbiodinium linuchaeae, and a thermally resistant non-native species, S. trenchii. Both of these were compared with the aposymbiotic condition of having no symbionts. It also sought to determine if protein expression changes occur between the day and night due to a lack of photosynthetic activity in the latter condition. The results demonstrated that anemones up- and down- regulate a core set of proteins as a function of symbiosis while also showing differential regulation depending on the type of Symbiodinium hosted. Differential expression between day and night conditions was more prominent in anemones hosting S. trenchii than those hosting S. linucheae when both are compared with aposymbiotic anemones.
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Emmanuel Salvador MedranoNutritional Impact on Rotenone-induced Parkinson's Disease in a Drosophila melanogaster Modelhttp://digitalcommons.fiu.edu/bio_honors/78
http://digitalcommons.fiu.edu/bio_honors/78Fri, 28 Apr 2017 08:15:29 PDT
Mitochondria act as the powerhouse of eukaryotic cells. These organelles are ultimately able to convert chemical energy from food into ATP through use of the electron transport chain. Dysfunction in the electron transport chain generates reactive oxygen species (ROS), which damage cells and can ultimately lead to their death. Recent work has implicated mitochondrial dysfunction and ROS as a hallmark of several neurodegenerative diseases, including Parkinson’s disease, suggesting a possible contribution to induction of neurodegeneration. The sporadic onset of Parkinson’s disease in the majority of cases raises the possibility that the environment is a significant modulator of mitochondrial function. Nutrient-responsive signaling processes are key regulators of autophagy, a process that recycles aged, malfunctioning mitochondria. To test whether nutrition affects onset of neurodegenerative phenotypes, we tested an established rotenone-induced Drosophila model of Parkinson’s disease. Using a climbing assay, it was found that both yeast and sucrose enhanced the phenotypes cause by the rotenone, yeast more so than sucrose. Mortality was also significantly increased by the yeast supplementation. These results indicate that dietary supplementation enhances neurodegenerative phenotypes, opening the way to investigation of specific signaling mechanisms.
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Laura PerezComparison of Navel and Laminar Stomata Morphology and Stomatal Conductance in the White Water Lily,Nymphaea odorata (Nymphaeaceae)http://digitalcommons.fiu.edu/bio_honors/77
http://digitalcommons.fiu.edu/bio_honors/77Fri, 28 Apr 2017 08:15:23 PDT
The white water lily, Nymphaea odorata, is an indicator species for the slough communities of the Everglades. Similar to other emergent aquatic plants, it has a gas flow-through system characterized by a pressure gradient that is controlled by differences in temperature and humidity between the inside and outside of the leaf. This flow-through system has not been completely described in N. odorata, but stomatal control may contribute to this system. The purpose of this study was to quantify stomatal size and density in the navel and lamina of N. odorata and determine if these morphological traits contribute to regulation of the flow-through system. Stomatal density, stomatal size, leaf area, and navel area were measured, in plants contained in high and low water treatments; stomatal measurements were made using compound microscopy and image processing was done with ImageJ software. Stomatal conductance, transpiration and leaf temperature were measured using a steady-state porometer in order to assess differences in gas exchange in different parts of the leaf and with different leaf ages. This study found that there is a large difference in navel and laminar stomata size with navel stomata being 2.4 times larger. There is also a difference in navel and laminar stomata density with laminar stomata being 10.44 times denser. Navel area forms a linear relationship with lamina area but only in the high water treatment. Porometer measurements showed that there were no differences in stomatal conductance, transpiration nor leaf temperature between the navel and lamina nor between old and new leaves. This study demonstrated that although navel and laminar stomata differ morphologically in N. odorata, they do not differ in stomatal conductance.
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Brianna Kaitlyn AlmeidaIdentification of Alginate-regulating Genes in the Clinical Cystic Fibrosis Isolate of Pseudomonas aeruginosa PA2192http://digitalcommons.fiu.edu/bio_honors/76
http://digitalcommons.fiu.edu/bio_honors/76Fri, 28 Apr 2017 08:15:16 PDT
Cystic fibrosis (CF) is a genetic disorder that leads to a buildup of mucus in the lungs ideal for bacterial colonization. When Pseudomonas aeruginosa enters the CF lung, it undergoes a conversion from nonmucoid to mucoid; colonization by a mucoid strain of P. aeruginosa greatly increases mortality. The mucoid phenotype is due to the production of alginate. The regulator of alginate production is the AlgT/U sigma factor which directs RNA polymerase to transcribe the alg regulon, thereby initiating alginate biosynthesis. The observed phenotypic conversion is due to a mutation in the mucA gene coding for an anti-sigma factor, MucA, which sequesters AlgT/U. This mucoid phenotype is unstable when the strains are removed from the lung as they acquire second-site mutations. This in vitro reversion phenomenon is utilized to identify novel genes regulating alginate production. Previously, second-site mutations were mapped to algT/U, algO, and mucP, demonstrating their role in alginate regulation. Most of these studies were performed using a non-CF isolate. It was hypothesized that second site mutations in a clinical strain would be mapped to the same genes. In this study, a clinical, hyper-mucoid P. aeruginosa strain PA2192 was used to study the reversion phenomenon. This study found that PA2192 has a novel mucA mutation which was named them mucA180 allele. Twelve colonies were sub-cultured for two weeks without aeration at room temperature and plated daily for single colonies in order to obtain nonmucoid suppressors of alginate production (sap). Only 41 sap mutants were stable for more than 48 hours — a reversion frequency of 3.9% as compared to ~90% in laboratory strains showing that PA2192 has a stable mucoid phenotype. This phenotype was restored in 28 of the 41 sap mutants when complimented with plasmids harboring algT/U. Four of the sap mutants are complemented by algO. Sequence analyses of the algT/U mutants have found a novel mutation in the promoter region.
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Brett ColbertMolecular Mechanisms Defining the Effect of Host Diet on Wolbachia Titer Suppression During Oogenesishttp://digitalcommons.fiu.edu/bio_honors/75
http://digitalcommons.fiu.edu/bio_honors/75Fri, 28 Apr 2017 08:14:58 PDT
Antibiotics have saved over 200 million lives, but excessive consumption has led to increasingly prevalent resistance. A potential solution is to stop pathogens from invading eukaryotic cells in the first place. This requires a mechanistic understanding of how host-endosymbiont relations are managed. Endosymbiotic Wolbachia bacteria are naturally carried by the well-studied host Drosophila melanogaster, providing an ideal model system for studying the cellular and molecular basis of infection. A 2015 study by Serbus et al. found that when fruit flies were fed dietary yeast, the titer of Wolbachia carried in oogenesis decreased. The molecular mechanisms facilitating this response are not well understood but are thought to be diet-driven insulin signaling. To investigate this further, fruit flies were exposed to nutrients, compounds and small molecule inhibitors to test specific hypotheses related to insulin signaling. The data suggest that the mechanism underlying how dietary yeast suppresses titer is initiated by insulin, and may involve multiple signaling branches. This mechanism requires ingestion of dietary yeast by the insect, allowing yeast-derived factors to trigger somatic insulin release. The oocyte Wolbachia respond to the yeast-enriched host environment through several behavioral and physiological changes. These include decreased bacterial counts, emphasized localization at the posterior pole, and a round nucleoid shape. The data suggest that these outcomes may be due to multiple effectors interacting within the insulin signaling and epidermal growth factor receptor pathways. These findings provide a foundation of knowledge to continue building upon, and ultimately clarify how host-diet manipulates titer, so as to maximize bacterial control.
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Mailin OlivaThe Role of Glucose Metabolism in Cardiovascular Calcification and Fibrosishttp://digitalcommons.fiu.edu/bio_honors/74
http://digitalcommons.fiu.edu/bio_honors/74Thu, 27 Apr 2017 09:01:12 PDT
Elevated glucose and insulin resistance are associated with the prevalence and progression of coronary artery calcification independently of metabolic syndrome. Diabetic patients often exhibit changes in the vessel wall tissue leading to fibrotic collagen and calcific mineral deposition, as opposed to a degenerative tissue remodeling mechanism. Extracellular vesicles (EV) control the deposition of calcific mineral in vascular tissue. Therefore, it was hypothesized that high extracellular glucose concentrations may lead to the release of a large number of EVs by the smooth muscle cells (SMCs) under osteogenic media with high-glucose concentration. To test this, SMCs were placed under normal or osteogenic media with different glucose concentrations (0 g/L-4.5 g/L), and the EVs were analyzed using the Izon qNano. Extracellular calcifications were measured using Alizarin Red S dye, and it was discovered that the absence of glucose results in the lack of extracellular calcification. Conversely, an increase in glucose leads to greater extracellular calcium deposition. These data indicate that the presence of glucose is necessary for extracellular calcification. It was initially suspected that more EVs would be released by SMCs under osteogenic media with high-glucose concentration; however, this was not the case and qNano analysis showed that more EVs were released with osteogenic media that lacked glucose. In addition, EVs in osteogenic high-glucose media presented a greater diameter than those in normal high-glucose media. These results could be consequence of mineral nucleation on EV surface reducing zeta potential. This study indicates a potential role of glucose in vascular wall tissue remodeling.
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Daniela MedinaEvaluating triclosan resistance and impact on community structure in the human skin microbiomehttp://digitalcommons.fiu.edu/bio_honors/73
http://digitalcommons.fiu.edu/bio_honors/73Thu, 27 Apr 2017 07:41:15 PDT
Bacteria can develop cross-resistance to more than one antibiotic after being exposed to other antimicrobial compounds such as triclosan (TCS, 5-chloro-2-(2,4-dichlorophenoxy)phenol). This raises concern since it is found in many personal care products such as deodorants and body washes in addition to the environment due to its unregulated disposal. Therefore, this study examined the antibiotic resistance of microbial communities of the skin with different exposures to TCS-containing topical products, as well as microbes from soil and sediment. Healthy volunteers were screened and organized into groups based on the use of deodorants, antiperspirants, and body washes that contained TCS or did not. Skin swab samples as well as microbes from environmental samples were cultured and isolates selected for further studies. Isolates were Gram-stained and tested for antibiotic resistance using the Kirby-Bauer method. Their ribosomal internal transcribed spacer (ITS) regions were amplified and sequenced to obtain the taxonomic identities. The trend towards greater resistance was observed among isolates from TCS-exposed skin as well as those from soil and sediment. Four skin isolates were identified as three separate species known to be transients or commensals of the skin microbiota. Further sampling and testing is needed to better understand if TCS exposure is increasing resistance in these communities.
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Kevin A. Fundora et al.Phyloextracts from Genus Artemisia: Controlling Survival and Melanogenesis of Murine Metastatic Cellshttp://digitalcommons.fiu.edu/bio_honors/72
http://digitalcommons.fiu.edu/bio_honors/72Wed, 26 Apr 2017 12:38:41 PDT
The study examined the effect of natural compounds found in Artemisia douglasiana and Artemisia tridentata extracts on survival and melanogenesis of B10F16 metastatic murine cells. The cells were exposed to short UVB and IBMX treatments to determine their ability to regulate melanogenesis. IBMX-treated cells showed a more robust effect on the production of melanin. B10F16 cells were treated with Artemisia tridentata and DhL, an active natural compound extracted from Artemisia douglasiana, showed a clear inhibitory effect in IBMX-stimulated cells. Tyrosinase activity was observed in supernatants after DhL and Artemisia tridentata extracts were added. Artemisia tridentata showed the strongest inhibitory effect on melanogenesis in vitro and utilized the tyrosinase pathway to prevent melanin production in B10F16 cells. Artemisia douglasiana showed an inhibitory effect of melanogenesis in vitro but it appears to use a different pathway to inhibit melanogenesis. Therefore, it is important to continue studying Artemisia tridentata and Artemisia douglasiana for their inhibitory properties on melanogenesis.
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Victoria GodievaRole of endothelin 3 on the angiogenic response of the tumor in a melanoma mouse modelhttp://digitalcommons.fiu.edu/bio_honors/71
http://digitalcommons.fiu.edu/bio_honors/71Mon, 02 May 2016 06:21:30 PDT
Over the past three decades, more people have been diagnosed with skin cancer than all other cancers combined. Melanoma is the most dangerous form of skin cancer because of its high propensity to metastasize. Several studies have shown that angiogenesis is crucial for the development and progression of the tumors in melanoma. Endothelin 3 (Edn3) is a ligand that binds to Endothelin receptor B (EdnrB), and has been linked to melanoma progression. I developed a highly metastatic mouse model of melanoma dependent on the over-expression of Endothelin 3 (Edn3). I crossed Dct-Grm1 transgenic mice, which aberrantly express metabolic glutamate receptor 1 and develop melanocytic hyperplasia, with K5-Edn3 mice, which conditionally overexpress Edn3 under the Keratin 5 promoter to generate Dct-Grm1/K5-Edn3 mice. Our preliminary data suggest that Edn3 enhances the angiogenic response of the tumors in the Dct Grm1/K5-Edn3 mice compared to controls. The goal of this study is to further investigate the effect of Edn3 in the development of new blood vessels and establish if this process is accompanied by the creation of hypoxic environment in the tumors. In order to visualize the density of blood vessels in the tumors I directly labeled them by cardiac perfusion using a lipophilic carbocyanine dye (DiI). I subsequently removed the tumors and quantified the amount of labeling using confocal microscopy. Diffuse reflectance spectroscopy and a novel spectral interpretation was employed to analyze and compare regions of oxygen saturation in tail tumors of the Dct-Grm1/K5-Edn3 mice and control population. My results indicate that the increased angiogenic response in the presence of Endothelin 3 is accompanied by a significant increase of hypoxic environments. Hindering the expression of Edn3 may serve as a potential starting point to the development of novel therapies to combat this lethal disease.
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Juan A. ValladaresAndrogen regulation of metabolic trade-offs between signaling and cellular metabolism in the electric fish Brachyhypopomus gauderiohttp://digitalcommons.fiu.edu/bio_honors/70
http://digitalcommons.fiu.edu/bio_honors/70Mon, 02 May 2016 06:21:23 PDT
All organisms are limited in the amount of energy they can spend, and therefore an increased spending in one function results in decrease in spending in another, creating an energetic trade-off. Androgens are known to increase signal size in male weakly electric fish, and a larger signal size requires more power and therefore more energy. I investigated if androgens act as a regulator for an energetic trade-off between signaling and cellular metabolism in male Brachyhypopomus gauderio. I measured the male’s oxygen consumption in a respirometry chamber under varying pharmacological challenges to partition the energy budget. Then I implanted the fish with 5α- dihydrotesosterone (DHT) and repeated the respirometry and pharmacological trials. I found that with elevated DHT levels males exert more power per signal and consume more oxygen for communication and less for standard metabolic functions. This research is the first to demonstrate an energetic trade-off between signaling and metabolism in electric fish.
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Alexis N. ArenalOptimizing the Genetic Toolkit for Aedes Aegypti Using Targeted Integration of Recombination Siteshttp://digitalcommons.fiu.edu/bio_honors/69
http://digitalcommons.fiu.edu/bio_honors/69Mon, 02 May 2016 06:21:16 PDT
The mosquito Aedes aegypti is a vector for several human pathogens that cause infectious diseases such as dengue fever, chikungunya, yellow fever, and zika. This animal has evolved a preference to blood feed from humans, making it a cause of high medical concern. A method often used to study the molecular and neural basis of behavior in model organisms such as Drosophila melanogaster is the GAL4/UAS system, which employs the yeast transcription factor gene GAL4 and its associated UAS binding sites to drive expression of effector transgenes. This technique is known for its versatility, but there are limits to what it can reveal if position effects on expression are not properly controlled. When a transgene is randomly inserted into the genome, nearby suppressors or enhancers of endogenous gene expression influence the transgene. Therefore, each site in the genome has a different effect on a given transgene’s expression. To control for this “position effect”, we need to insert transgenes into the same location. The main objective of this work is to insert an attP recombination site into a number of A. aegypti eye pigment genes, to create docking strains for transgene integration that control for position effects and have visually recognizable phenotypes. An oligo containing homologous sequences and the attP site are co-injected into embryos with CRISPR/Cas9, which makes a double stranded break to disrupt the eye pigment genes white (w), scarlet (St), pink (P), cinnabar (Cn), sepia (Se) and ruby (Rb) and produce their respective eye phenotype. Once the attP is in place, any effector transgene can be inserted into the genome through recombination with a plasmid- bound attB site, causing the subsequent descendants to exhibit the same level of expression of that construct. A mixture containing the designed sgRNA, Cas9 protein, the attP oligo and water, was injected into pre-blastoderm embryos. DNA extraction and fragment analysis were used to identify the attP insertion in the mosaic G0’s. The attP site was also detected in later generations for the genes White and Scarlet. Once characterized, the docking lines will be used to introduce a UAS-luciferase construct into the mosquito genome. The level of chemiluminescence will serve as an indication of the expression of the UAS and whether position effects are controlled. This work represents a new approach to understand mosquito host detection at the molecular and cellular level.
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Ileana Daniela CorsiMorphological and Molecular Approach to the Reclassification of Laurencia Cervicornis (Ceramiales, Rhodophyta) Populations and the Effect of Herbivory on its Abundance on Coral Reefshttp://digitalcommons.fiu.edu/bio_honors/68
http://digitalcommons.fiu.edu/bio_honors/68Mon, 02 May 2016 06:21:09 PDT
The Laurencia complex encompasses multiple species of red macroalgae commonly present on coral reefs. While some species are usually chemically defended and abundant, others are palatable, cryptic and could constitute part of the diet of herbivorous fish. However, field and laboratory species identification of the Laurencia complex is difficult because of their morphological similarities, which limit ecological and morphological studies at the species level. This research identifies and describes the morphology and the ecological pressures of the common species, Laurencia cervicornis. To evaluate seasonality of L. cervicornis in the absence of herbivory, limestone tiles (n=32) were placed in herbivores exclosure treatments at Pickles reef during Aug. 2011- Mar. 2012 to recruit L. cervicornis. Seasonal abundance was recorded and samples were collected for morphological and genetic studies. In November 2015, feeding assays were conducted at Conch Reef to evaluate the herbivory impact on algal species including L. cervicornis. A marked seasonality of algal abundance within the exclosures was reported, with a low abundance (~6%) of L. cervicornis in spring and almost completely disappearing in winter (0%). The abundance of L. cervicornis dropped in the first four hours of exposure of the tiles to herbivores, suggesting the effectiveness of grazers controlling this species. The specimens recruited on the tiles display diagnostic characteristics typical of the genera Chondrophycus and Palisada. Reproductive structures were reported for the first time and were consistent with this view. The phylogenetic position of this species was inferred by an analysis of chloroplast-encoded rbcL gene sequences of 53 taxa, using two members of the Rhodomelaceae and two of the Ceramiaceae as outgroups. The samples of L. cervicornis showed 0.2-0.9% genetic divergence indicating that all represent the same species. In all analyses, Laurencia cervicornis was phylogenetically distant from the genus Laurencia, and joined with Palisada with high support. On the basis of both molecular and morphological data, L. cervicornis should be transferredto the genus Palisada, but in order to rename and transfer L. cervicornis to Palisada, morphological characteristics will require revision.
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Elizabeth ArmenisDissecting the Relationship Between Allatotropin Signaling and Juvenile Hormone Synthesis in Aedes Aegyptihttp://digitalcommons.fiu.edu/bio_honors/67
http://digitalcommons.fiu.edu/bio_honors/67Mon, 02 May 2016 06:21:01 PDT
Aedes aegypti is a vector for the majority of mosquito-borne illnesses. The capability of this vector depends on the need for female mosquitoes to feed on human blood to nourish their eggs. The female mosquitoes ability to find human hosts is dependent on both odor detection and changes in neural circuits in the brain. In A. aegypti, Juvenile Hormone is stimulated in vitro by the neuropeptides allatotropins (AT) and inhibited by allatostatins (AS), which are secreted from the brain and target the corpora allata. Allatotropin in A. aegypti has been shown to stimulate JH synthesis in the corpora allata in ex vivo studies. Due to its connection with Juvenile Hormone synthesis, allatotropin is likely an essential factor contributing to reproductive maturation and the gonotrophic cycle in A. aegypti. Although addition of allatotropin to the corpora allata ex vivo has been shown to stimulate synthesis of JH, its role in vivo has not been described. Here I use CRISPR/Cas9 genome editing to excise the allatotropin neuropeptide and make two null mutant lines. A deletion formed by non-homologous end joining, ATdel, and a 50bp insertion of a docking strain using homology dependent repair, ATattP. These mutants show a significant divergence from expected Mendelian ratios (ATdel p=2.05x10- 16, df=2 and ATattP p=0.003, df=2). The genotypic divergence from expected genetic ratios seen in the offspring of two heterozygous progenitors in both mutant lines shows lethality of the mutation suggesting that the Allatotropin neuropeptide plays a significant role in the physiology of the mosquito. Apart from these results, the ATdel and ATattP mutants have the ability to produce eggs and undergo ovarian maturation. Further understanding of this neuropeptide can uncover its role in nutrition, development and its contribution to JH biosynthesis.
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John S. CastilloThe Relationship of Heteroptera Species Richness, Abundance, and Morphology to Elevation Gradients and Land-use Regimes on Mt. Kilimanjarohttp://digitalcommons.fiu.edu/bio_honors/66
http://digitalcommons.fiu.edu/bio_honors/66Wed, 29 Apr 2015 05:40:55 PDT
Insect biodiversity is unevenly distributed on local, regional, and global scales. Elevation is a key factor in the uneven distribution of insect diversity, serving as a proxy for a host of environmental variables. My study examines the relationship of Heteroptera (true bugs) species diversity, abundance, and morphology to elevational gradients and land-use regimes on Mt. Kilimanjaro, Tanzania, East Africa. Heteroptera specimens were collected from 60 research sites covering an elevational range of 3684m (866-4550m above sea level). Thirty of the sites were classified as natural, while the remaining 30 were classified as disturbed (e.g., agricultural use or converted to grasslands). I measured aspects of the body size of adult specimens and recorded their location of origin. I used regression models to analyze the relationships of Heteroptera species richness, abundance, and body measurements to elevation and land-use regime. Richness and abundance declined with greater elevation, controlling for land use. The declines were linear or logarithmic in form, depending on the model. Richness and abundance were greater in natural than disturbed sites, controlling for elevation. According to an interaction, richness decreased more in natural than disturbed sites with rising elevation. Body length increased as a quadratic function of elevation, adjusting for land use. Body width X length decreased as a logarithmic function of elevation, while leg length/body length decreased as a quadratic function. Leg length/body length was greater in disturbed than natural sites. Interactions indicated that body length and body width X length were greater in natural than disturbed sites as elevation rose, although the general trend was downward. Future research should examine the relative importance of land area, temperature, and resource constraints for Heteroptera diversity and morphology on Mt. Kilimanjaro.
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Joseph P. TardanicoUnderstanding the role of Dimethylsulfoniopropionate as a potential chemotactic cue for coral-associated bacteriahttp://digitalcommons.fiu.edu/bio_honors/65
http://digitalcommons.fiu.edu/bio_honors/65Tue, 28 Apr 2015 12:00:48 PDT
Most reef-building corals are known to engage in non-pathogenic symbiosis not only with unicellular dinoflagellates from the genus Symbiodinium, but also with other microscopic organisms such as bacteria, fungi, and viruses. The functional details of these highly complex associations remain largely unclear. The impetus of this study is to gain a better understanding of the symbiotic interaction between marine bacteria and their coral host. Studies have shown that certain bacterial orders associate with specific certain coral species, thus making the symbiotic synergy a non-random consortium. Consequently both corals and bacteria may be capable of emitting chemical cues that enable both parties to find one another and thus generate the symbiosis. The production of these cues by the symbionts may be the result of environmental stimuli such as elevated ocean temperatures, increased water acidity, and even predation. One potential chemical cue could be the compound DMSP

(Dimethylsulfoniopropionate) and its sulphur derivatives. Reef-building corals are believed to be the major producers of the DMSP during times of stress. Marine bacteria utilize DMSP as a source of sulfur and carbon. As a result corals could potentially attract their bacterial consortium depending on their DMSP production. This would enable them to adapt to fluctuating environmental conditions by changing their bacterial communities to that which may aid in survival. To test the hypothesis that coral-produced DMSP plays a role in attracting symbiotic bacteria, this study utilized the advent of high-throughput sequencing paired with chemotactic assays to determine the response of coral-associated bacterial isolates towards the DMSP compound at differing concentrations. Chemotaxis assays revealed that some isolates responded positively towards the DMSP compound. This finding adds to existing evidence suggesting that coral-associated pathogens utilize chemotaxis as a host colonization and detection mechanism. Thus the symbiotic bacteria that make up the coral microbiome may also employ this process. Furthermore this study demonstrates that bacterial motility may be a strong contributing factor in the response to the chemotactic cue. Swarming motility may be better suited for bacteria that need to respond to a chemical gradient on the surface of the coral. Therefore the isolates that were able to swarm seemed to respond more strongly to the DMSP.

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Leidy C. GonzalezProteomic Analysis of Wolbachia Symbiosis Within the Drosophila Ovaryhttp://digitalcommons.fiu.edu/bio_honors/64
http://digitalcommons.fiu.edu/bio_honors/64Tue, 28 Apr 2015 11:25:52 PDTWolbachia pipientis are bacterial endosymbionts carried by millions of invertebrate species, including ~40% of insect species and some filarial nematodes. In insects, basic Wolbachia research has potential applications in controlling vector borne disease. Conversely, Wolbachia of filarial nematodes are causative agents of neglected tropical diseases such as lymphatic filariasis and African river blindness. However, remarkably little is known about how Wolbachia interact with their hosts at the molecular level. Understanding this is important to inform the basis for symbiosis and help prevent human disease. I used a high-throughput proteomics approach to study how Drosophila host cells are modified by Wolbachia infection. This analysis identified 23 Drosophila proteins that significantly changed in amount as a result of Wolbachia infection. A subset of differentially abundant host proteins were consistent with Wolbachia-associated phenotypes reported previously. This study also provides the first ever discovery-based evidence for a Wolbachia-associated change in maternal germline histone loads, which has possible implications in Rescue of a common Wolbachia-induced reproductive manipulation known as Cytoplasmic Incompatibility.
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Ricardo PerezUsing stable isotopes to investigate trophic interactions of bottlenose dolphins (Tursiops truncatus) in the Florida Coastal Evergladeshttp://digitalcommons.fiu.edu/bio_honors/63
http://digitalcommons.fiu.edu/bio_honors/63Tue, 28 Apr 2015 11:20:53 PDT
Top predators are known for their ability to 1) affect their communities through predation and 2) induce behavioral modifications. Recent research suggests that they may also play “bottom-up” roles in ecosystems, including transporting materials within and across habitat boundaries. The Florida Coastal Everglades (FCE) is an “upside-down” oligotrophic estuary where productivity decreases from the mouth of the estuary to freshwater marshes. Therefore, movements of predators may be important in ecosystem dynamics. While other estuarine predators in the FCE have been shown to potentially move nutrients among ecosystems, the potential for bottlenose dolphins (Tursiops truncatus) to play a similar role in the systems has not been investigated. Stable isotope analysis of biopsy samples were used to investigate spatial variation in trophic interactions of dolphins to see if they might transport nutrients. Values of δ15 N suggest dolphins feed at a trophic level similar to other top predators in the ecosystem while δ13 C suggest that dolphins forage largely within food webs where they were sampled rather than transporting nutrients across ecosystem boundaries. The exception may be dolphins foraging in rivers, which may transport nutrients downstream; a pattern opposite to that of bull sharks and alligators in these habitats. Further research is necessary to predict how future changes occurring due to restoration and climate will affect the ecological roles of dolphins.
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Valerie A. PazEffects of a Visual Horizon on Drosophila Melanogaster Object-Tracking Responseshttp://digitalcommons.fiu.edu/bio_honors/62
http://digitalcommons.fiu.edu/bio_honors/62Tue, 28 Apr 2015 11:20:52 PDT
To navigate effectively in three-dimensional space, flying insects must approximate distances to nearby objects. Humans are able to use an array of cues to guide depth perception in the visual world. However, some of these cues are not available to insects that are constrained by their rigid eyes and relatively small body size. Flying fruit flies can use motion parallax to gauge the distance of nearby objects, but using this cue becomes a less effective strategy as objects become more remote. Humans are able to infer depth across far distances by comparing the angular distance of an object to the horizon. This study tested if flying fruit flies, like humans, use the relative position of the horizon as a depth cue. Fruit flies in tethered flight were stimulated with a virtual environment that displayed vertical bars of varying elevation relative to a horizon, and their tracking responses were recorded. This study showed that tracking responses of the flies were strongly increased by reducing the apparent elevation of the bar against the horizon, indicating that fruit flies may be able to assess the distance of far off objects in the natural world by comparing them against a visual horizon.
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Jorge L. CaballeroAn overview on Human Leukocyte Antigen (HLA) region gene expression during Pseudomonas aeruginosa infectionhttp://digitalcommons.fiu.edu/bio_honors/61
http://digitalcommons.fiu.edu/bio_honors/61Mon, 27 Apr 2015 05:40:56 PDT
The human leukocyte antigen (HLA) complex is an extensively studied cluster of genes with immunoregulatory function. Pseudomonas aeruginosa is capable of infecting individuals with weakened immune systems, and is associated with a high mortality rate. Previous genetic studies of the HLA region have found correlations between bacterial infection and its effect on regulating HLA gene expressions to establish their infection. This project analyzes the expression of classical HLA loci (A, B, C, DR, DQ, DP) in human B cells and macrophage cells during the infection of virulent strains of P. aeruginosa. Cells were cultured and infected with different virulent live, and heat-killed strains of P. aeruginosa for different time periods. The mRNA was extracted and converted into cDNA followed by real-time quantitative PCR and data analysis. The Western Blot technique was used to identify the targeted protein’s cell surface expression. Infection with P. aeruginosa was found to inhibit the expression of HLA proteins. The PA14 strain inhibited expression of all targeted genes in all experiments. Infections with PA01 and PA103 showed different patterns depending on the incubation time and the targeted gene. These differences suggest that the three strains use various mechanisms to inhibit HLA protein expression.
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Daniela Florit